Miniaturized microphones can be produced in MEMS construction. A known operating principle consists in the measurement of a capacitance between a membrane excited into vibration by sound and an adjacent fixed counter electrode.
As a rule, a MEMS microphone is made from a MEMS chip of a thickness of a few 100 μm that has one or more membranes of a thickness of a few 100 nm. Normally, the membrane structures are formed essentially flush with a surface of the MEMS chip. The opposite surface then has a recess in the membrane region. This recess can be made available for the enclosed rear volume that is required for the microphone function and that is used as a static reference for the detection of the variable sound pressure.
The general trend toward miniaturization and cost reasons require smaller surface areas for the MEMS chip. Associated with this, however, is also a simultaneous reduction in the rear volume that can be achieved by the recess. When the membrane is deflected, however, this leads to an increased counter pressure that, in turn, prevents the deflection and that results in reduced sensitivity and worse noise properties.
From the U.S. Patent Application Publication No. US 2005/0185812, a microphone housing is known in which a microphone formed as a MEMS component is arranged together with a semiconductor chip on a base plate. The MEMS package includes a common cap with which the MEMS component is covered opposite the base plate.
A disadvantage in this configuration, however, is the relatively large component volume and the small portion of this volume used acoustically.